The present invention relates to a three-dimensional information processing method and apparatus and, more particularly, to a three-dimensional information processing method and apparatus for measuring the shape of an object with an active method.
As a conventional method for obtaining information associated with a three-dimensional shape using an image sensor or the like, a light-cutting method (slit method), a stereo method, and the like are known.
In the light-cutting method, slit light is projected onto the surface of an object, and the projected beam is observed from a direction different from the projection direction, thereby obtaining information such as a sectional shape of an object, a distance to the object, and the like. With this method, a plurality of images are imaged slit by slit by a stationary imaging means while the slit projection direction is changed slightly for each projection, thereby obtaining three-dimensional information.
In the stereo method described in U.S. patent application Ser. No. 706,727 filed be the same assignee of the present invention, a pair of two-dimensional imaging elements combined with an optical system and having an equal image magnification are arranged to be separated by a predetermined base length, and two-dimensional images of an object viewed in different directions are obtained thereby. Then, a distance from each position of the object to the imaging system is calculated from a deviation between the two pieces of image information.
In the light-cutting method, however, control of the slit projection direction during imaging is cumbersome, and imaging is time-consuming. Since the three-dimensional information is obtained from a plurality of slit images, a large volume of information is to be processed, and a great deal of time is required for obtaining final information.
In the stereo method, slit scanning control is not required However, the conventional methods normally adopt a passive method. Therefore, when an object has a smooth surface and exhibits a uniform luminance, a contrast between images obtained by two imaging elements is decreased, and distance measurement by comparing two images is rendered impossible. Such a case frequently occurs in a near distance with a large image magnification. Therefore, the shape, color, size, and distance of an object which can be measured are limited.